Conduction Disorders

PA Study Sesh

This week on PA Study Sesh we are starting the cardio chapter and discussing conduction disorders.
Sinus Arrhythmia
* Appears as normal sinus rhythm, but rhythm is irregular
* Normal variant
* INcreases during INspiration
Sinus Bradycardia
* <60BPM
* #1cause=vagal stimulation=increased acetylcholine (increased parasympathetic activity)
* Tx: Atropine (anticholinergic)
Sinus Tachycardia
* >100BPM
* Tx: Vagal maneuvers, adenosine, bblockers, CCB, Digoxin (ABCDs)
Sick-Sinus Syndrome
* Combo of sinus arrest with paroxysms of tachy & brady arrhythmias
* TX: permament pacemaker if symptomatic
* If V-tach=with automatic implanatable cardioverter-defibrillator
Premature Atrial Contraction (PAC)
* Abnormal P wave followed by QRS
* May be unifocal or multifocal
* Non-compensatory pause
* Next normal p wave is not where expected
* Usually benign, though may increase risk of arrhythmias if combined with other heart abnormalities.
Atrial flutter
* “saw tooth” waves
* Tx:
* Stable: vagal maneuvers, b-blockers, ccbs
* Unstable: synchronized cardioversion
* Definitive= ablation
Atrial fibrillation
* #1 chronic arrhythmia
* Irregularly irregular with narrow QRS
* No distinct P waves
* Loads of causes
* Often associated with hyperthyroid
* Also atrial enlargement
* Increased risk of clots (blood isn’t moving properly out of atria)
* Tx:
* Stable: rate control
* B blockers #1: metoprolol
* CCBs: Diltiazem or Verapamil (nondihydropyridines)
* Digoxin if hypotensive or CHF
* Unstable:
* Synchronized cardioversion
* Management:
* Anticoagulation
* Factor Xa inhibitors
* “Xabans”
* Bind to antithrombin III
* Dabigatran
* Direct thrombin inhibitor
* Warfarin
* If other drugs contraindicated
* Dual anti-platelet therapy
* Aspirin + Clopidogrel
* Less effective than anticoagulant monotherapy
Paroxysmal Supraventricular Tachycardia (PSVT)
* 2 types
* AV nodal reentry #1
* 2 paths within AV node (one slow & one fast)
* Av reciprocating
* Accessory pathway outside the av node
* Wolff-Parkinson White
* Lown-Ganong-Levine Syndrome
* Wide or narrow QRS complex
* Depends on which pathway is taken first
* Wolf-Parkinson White
* Accessory pathway=bundle of Kent
* Ventricles are “pre-excited”
* Can develop tachyarrhyhmias
* EKG:
* Delta wave
* Slurred QRS
* Candle
* Wide QRS
* Short PR Interval
* Management:
* Avoid av nodal blockers because current may preferentially travel down accessory pathway
* Lown-Ganong-Levine Syndrome
* Short PR interval with normal QRS
* Bundle of James
* Management (of all PSVT)
* Narrow complex
* Vagal maneuvers
* =increased acetylcholine=decreased heartrate
* Adenosine#1
* B or CCBs
* Wide Complex
* Amiodarone